Thousands, perhaps millions, of dollars are spent annually for the purchase of highly colored fishing lures by sportsmen, and it is a widely held belief that bass, under some environmental circumstances, prefer one color or combinations of colors to the colors preferred by the bass under different circumstances.
The color vision of fish has been scientifically investigated, as have the ways in which variations in water depth and turbidity affect the properties of light transmitted therethrough. There appears to be little agreement, however, as to how the color perception of fish compares to that of humans, or how the location of mature game fish in various kinds of water, and under various ambient light conditions, affects the way a particular species of fish envisions a colored object located in relatively close proximity to such fish.
In U.S. Pat. No. 3,897,157 issued to McLaughlin et al, a colorimeter described as useful in selecting a particular color of fishing lure for use in fishing is described. In the McLaughlin device, a probe which can be lowered into the water is provided and is constructed to provide a plurality of prism-shaped photocells disposed inside a plurality of serially and vertical stacked circular light filter discs. This instrument is connected to a readout device at the surface.
The photocells utilized are selected to have a particular resistance which varies with the intensity of light impinging on the photocells. The filters are selected so that each filters white light so as to direct light of a particular wave length onto one of the respective photocells. By means of this device, including the matched color filters and associated photocells, the device provides at the readout instrument located at the surface, a visual indication of the relative intensities of different colors of light below the surface of the body of water. Thus, if the color blue is shown by the instrument to be more intense than the color red, the theory of operation and use of the device is that blue is the color which would be better seen by fish at the location where the probe is located in the water, and that a blue lure should be used by the fisherman. In other words, the instrument measures the intensity of light of different wavelengths at a particular depth in the water, and that wavelength which is most intense at that depth, as determined by the particular photocell sensitive to that color is the color which, in theory, the fish should see best.
This device is, of course, based on the supposition that the fish sees light as does a human, and that the color of lure which will be best seen by the fish is the color of lure which corresponds in its color to a particular part of the visible spectrum which is more intesne at the particular depth in question. Thus, the assumption is, that having broken apart white light at the depth at which the probe is located, that part of the spectrum corresponding to a particular color of a specific wavelength which is of the greatest intensity will be the color best seen by the fish. As hereinafter shown, other workers have not agreed that light intensity is of equal or greater importance than wavelength difference. In other words, other theories would say that even though blue, for example, may be the most intense monohcromatic color at a given depth and under given environmental conditions, a bass fish will still be more attrated to a red lure than to a blue lure.
The studies of Schiemenz in 1924 and Wolff in 1926 demonstrated that fish tested were able to distinguish among about twenty colors of the visible spectrum, and also ultraviolet, by reason of the wavelength of the color, as opposed to the brightness of a particular color.
In 1937, F. A. Brown concluded that bass see colors in about the same way that humans would perceive the same colors when viewing them through a yellowish filter. He further concluded that both wavelength and intensity play a part in the ability of the bass to see certain colors. His research indicated that red was the most readily perceptible color to the bass, followed by yellow, with blue and black being much less perceptible. The Brown research, however, was carried out with very young bass not exceeding about one to two inches in length, and was carried out under laboratory conditions in water of unreported clarity, and under an illumination of from 12 to 20-foot candles. No attempt was made to simulate varying ambient light due to changing atmospheric conditions, or to vary the clarity of the water used in the experiments. Illinois Natural History Survey Bulletin, Vol. 21, Art. 2, May, 1937.
In studies carried out by the Bureau of Medicine and Surgery of the Navy Department, and reported in the Journal of the Optical Society of America, Vol. 57, No. 6, p. 802, 1967, the underwater visibility to scuba divers of various colors, both fluorescent and non-fluorescent, was measured in four different bodies of water which were selected to sample the continuum from very murky to clear. The studies determined that fluorescent colors were always more visible than non-fluorescent, and that various colors were better seen under different water conditions. Blue-green color of a wavelength of 480 nm was best seen in pure water of good clarity. As the water becomes less clear, the peak of the light transmittance curve for various colors moved from 480 nm toward the longer wavelengths. One of the interesting observations resulting from these experiments was that, while there were certainly variations of the spectral distribution of natural daylight in water due to atmospheric conditions, such as a rainy day versus a sunny day, these were minor in their effect upon color visibility to the divers compared to the turbidiy or clarity of the water. In very murky, highly stained or muddy water, the colors best seen by the scuba divers when viewed horizontally at a depth of about five feet in the water were white, yellow and orange in non-fluorescent colors and yellow-orange, orange and red-orange in fluorescent colors. The most difficult colors to see in this type of water were black, gray, blue and green. In very clear water, blue and yellow non-fluorescent colors were relatively easily seen and fluorescent green and white were highly visible.
In waters of medium clarity (some sight murkiness) white, yellow and orange (all non-fluorescent) were readily seen, as were the fluorescent orange and fluorescent green colors. The lowest visibility was found to characterize gray, blue, green and black. It should be pointed out that these tests determined which of the various colored objects viewed by the divers were seen most accurately in terms of their ability to correctly identify the color of the object. The results, however, indicated that some colors were seen by the divers in certain of the waters in which the tests were conducted as different colors (from their appearance above water), and in such case, no consideration was given to the fact that the object, although seen as a certain incorrect color, was nevertheless seen clearly and perhaps better than in the instance where the object was seen as the correct color, i.e., the color which is used to describe the object if viewed in ambient light above the surface of the water. A conclusion drawn from the tests was then, in general, the wavelength of the actual color of the object tended to shift toward a longer wavelength as the murkiness or muddiness of the water increases and clarity decreases. Thus, blue tended to be seen as green, and yellow tended to be seen as orange and orange tended to be seen as red. In clear water the opposite tendency was observed.
A device for measuring and indicating the light intensity level at various depths in the water for the purpose of indicating light intensities at such depths to the fisherman is described in Harcrow, Jr. U.S. Pat. No. 3,876,312. A control means located at the surface which receives a signal from the water turbidity measuring device located at a certain depth displays on a readout instrument, the percentage of light present at the light sensing device relative to the surface light (or other standard). The Harcrow light intensity measuring and indicating device does not, however, provide any indication of the color which fish perceive best, or, more importantly, are most attracted to, under the measured light intensity, and in waters of varying clarity.
In 1976, Professor Don McCoy at the University of Kentucky carried out a number of experiments having as their objective determining how largemouth bass learn and perceive color. As a result of these experiments, all of which were conducted in an aquarium with clear water and simulated natural light, McCoy concluded that bass can clearly discriminate between a variety of colors; that a preference, under the testing conditions used, is demonstrated for the color green, and that wavelength is much more important in the ability of the bass to perceive and strike at colored targets than is the brightness of the target. Variation in target brightnesses, no matter what the color used, did not give rise to any significant difference in the basses' inclinations to strike the target. McCoy recognized that the deduced facts as to the inclination of the bass to strike targets of various color may be altered as a function of other variables which were not examined in the McCoy experiments, such as water clarity, and varying ambient light conditions. The McCoy experiments, in addition to suggesting that the bass demonstrated a preference for the color green relative to other colors under the conditions of the tests, further suggested that the bass demonstrates a slight aversion to the color yellow.
According to the Eastman Kodak Company in the publication, "The Fifth And Sixth Here's How", Combined Edition, 1977, pages 38-39, as light penetrates deeper below the surface of the water, the colors of the spectrum are selectively absorbed. The blue-green color of the water is said to act as a filter, absorbing colors at the red end of the spectrum. This statement, however, presupposes that the water is blue-green in color, and appears to be referring to the oceans, seas, and certain large bodies of fresh water, as opposed to some other smaller lakes where the color of the water may be brownish, reddish or even approach black in rare instances. In any event, in water of a blue-green color, progressively less red and orange light reaches underwater subjects, and thus these colors become progressively less perceptible at greater depths. Red, in fact, becomes reduced in its intensity at about ten feet in such water and at about twenty-five feet, red begins to appear brownish black. Orange becomes greenish in color at about thirty feet and yellow also becomes greenish in color at a depth slightly greater than thirty feet in blue-green water. In this type of water, the greens do not change color or fade until depths of 100 feet or more are reached.
The Kodak article states that one interesting exception to the manner in which long wavelength colors fade away to different colors as depth increases occurs in the case of the fluorescent dyes, which retain their normal hues, regardless of depth.
In his book, "The Silent World", Jacques Cousteau suggests that the angle of the sun over the surface of the water (i.e., the time of day) is much more important to the amount of light which penetrates the water to a significant depth than is the sky condition. He explains that this is so because at mid-morning, noon and mid-afternoon, the sun's rays strike the surface of the water more directly, rather than at a glancing angle, and thus more of the light enters the water as a result of less reflectance at these times as compared to early morning or dusk. Cousteau also recognized that the sea, by reason of its color, is a bluing agent, turning the appearance of articles at substantial depths blue. Cousteau confirmed that at fifteen feet, red turns to pink, and at forty feet becomes virtually black. At about this depth, orange also disappeared and at substantially greater depths, yellow began turning to green. Cousteau describes an underwater spear fishing expedition in which a fish species was harpooned at a depth of 120 feet, and blood which issued from it at that depth was green in color. As the spear fishermen moved toward the surface, the blood turned dark brown at fifty-five feet and at twenty feet turned pink. On the surface, it flowed red.
Within the experience of Homer Circle, well-known angling editor, as reported in Sports Afield, March, 1973, page 46 et seq., red, one of the traditionally best bass-catching colors, remains red until just before it turns black as the depth at which it is viewed increases. Yellow turns white shortly before the red turns to black, but remains visible as white much longer than the red continues to be visible. According to Circle, at some depth, the red disappears and cannot be seen. Chartreuse remained visible to a greater depth than yellow. Circle confirmed the great depths to which fluorescent colors remain visible as the same color as seen at the surface. Blue and purple remain visible to the greatest depths, although both blue and purple take on variable shades of dark violet at greater depths. The particular ambient light conditions prevailing over the water during the Circle observations were not reported. The water was reported as of good clarity.